Barnes slave-boson approach to the two-site single-impurity Anderson model with non-local interactionR. Frésard1, H. Ouerdane1, 2 and T. Kopp3
1 Laboratoire CRISMAT UMR CNRS-ENSICAEN 6508 - 6 Bld. Maréchal Juin, 14050 Caen Cedex, France, EU
2 LASMEA, UMR CNRS-Université Blaise Pascal 6602 - 24 avenue des Landais, 63177 Aubière Cedex, France, EU
3 Center for Electronic Correlations and Magnetism, EP VI, Universität Augsburg - D-86135 Augsburg, Germany, EU
received 29 January 2008; accepted in final form 14 March 2008; published May 2008
published online 17 April 2008
The Barnes slave-boson approach to the single-impurity Anderson model extended by a non-local Coulomb interaction is revisited. We demonstrate first that the radial gauge representation facilitates the treatment of such a non-local interaction by performing the exact evaluation of the path integrals representing the partition function, the impurity hole density and the impurity hole density autocorrelation function for a two-site cluster. The free energy is also obtained on the same footing. Next, the exact results are compared to their approximations at saddle-point level, and it is shown that the saddle point evaluation recovers the exact answer in the limit of strong non-local Coulomb interaction, while the agreement between both schemes remains satisfactory in a large parameter range.
11.15.Tk - Other nonperturbative techniques.
11.15.Me - Strong-coupling expansions.
71.27.+a - Strongly correlated electron systems; heavy fermions.
© EPLA 2008